GitHub MCP Server

Instructions

Implementation Reference

• index.ts:324-335 (handler)

  MCP CallToolRequest handler for 'create_branch': validates input schema, calls createBranchFromRef, and returns JSON response.

  case "create_branch": {
    const args = branches.CreateBranchSchema.parse(request.params.arguments);
    const branch = await branches.createBranchFromRef(
      args.owner,
      args.repo,
      args.branch,
      args.from_branch
    );
    return {
      content: [{ type: "text", text: JSON.stringify(branch, null, 2) }],
    };
  }

• operations/branches.ts:11-16 (schema)

  Zod input schema definition for the create_branch tool, used for validation in handler and JSON schema conversion.

  export const CreateBranchSchema = z.object({
    owner: z.string().describe("Repository owner (username or organization)"),
    repo: z.string().describe("Repository name"),
    branch: z.string().describe("Name for the new branch"),
    from_branch: z.string().optional().describe("Optional: source branch to create from (defaults to the repository's default branch)"),
  });

• index.ts:111-113 (registration)

  Tool registration in the ListTools response, providing name, description, and input schema.

  name: "create_branch",
  description: "Create a new branch in a GitHub repository",
  inputSchema: zodToJsonSchema(branches.CreateBranchSchema),

• operations/branches.ts:75-92 (handler)

  Primary handler logic: determines source SHA (from specified branch or default) and invokes createBranch.

  export async function createBranchFromRef(
    owner: string,
    repo: string,
    newBranch: string,
    fromBranch?: string
  ): Promise<z.infer<typeof GitHubReferenceSchema>> {
    let sha: string;
    if (fromBranch) {
      sha = await getBranchSHA(owner, repo, fromBranch);
    } else {
      sha = await getDefaultBranchSHA(owner, repo);
    }
  
    return createBranch(owner, repo, {
      ref: newBranch,
      sha,
    });
  }

• operations/branches.ts:41-60 (helper)

  Core utility: Makes POST request to GitHub Git Refs API to create the new branch reference.

  export async function createBranch(
    owner: string,
    repo: string,
    options: CreateBranchOptions
  ): Promise<z.infer<typeof GitHubReferenceSchema>> {
    const fullRef = `refs/heads/${options.ref}`;
  
    const response = await githubRequest(
      `https://api.github.com/repos/${owner}/${repo}/git/refs`,
      {
        method: "POST",
        body: {
          ref: fullRef,
          sha: options.sha,
        },
      }
    );
  
    return GitHubReferenceSchema.parse(response);
  }